Brake drum and method of making same



' June 24,1930- v G. M. EVANS 1,767,522

HRAK! DRUI AND METHOD OF BAKING SAME Filed July 14, 1927 INVENTOR:

BY oraZonME'dqms;

, ATTORN;Q%

Patented June 24, 1930 UNITED srAT s PATENT OFFICE eoanoN u. EVANS, or nErnorr, mcnIeAN, AssmNoE '10 mm WHEEL courm,

or PHILADELPHIA, PENNSYLVANIA, a CORPORATIO E rENNsYLvANm' BRAKE mum: AND mE'r zon or uaxme SAME Application filed July 14, 1927. SerialiRo. 205,572.

This invention relates to brake drums for vehicle wheels and to the method of making the same. a a

The practice heretofore has been to form I brake drums in a die drawing operation. The drum blank is cut from a square blank and the percentage of waste materialis compara tively hi h. In addition to this, considerable brea age results from the die-drawing of the drum flange, and consequently brake drum manufacture, employin the old methods, is not an economica proposition. Among other disadvantages contributing to the high cost of drum manufacture may be mentioned the. difliculty of die drawing a drum flange to the exact necessary diameter and the relatively great extent of floor space required for the storage of the drums prior to their incorporation into the wheel structure. The latter disadvantage results from the shape of the drums and the impossibility of nesting them. All such disadvantages I have efiectively eliminatedin the brake drum of my invention.

a brake drum for vehicle wheels characterized by a degree of economy of manufacture never heretofore attained in the art.

Other objects and advantages of my invention will become apparent as the description thereof proceeds.

With reference to the drawings forming a part of this a plication,

Fig. 1 is an e evational view of a brake drum constructed in accordance with my invention,

Fig. 2 is a sectional view, on an enlarged scale, on line 2- 2 of Fig. 1,

Fig. 3 is a plan view of a metal strip from which the drum flange is formed,

Fig. 4 is a cross-sectional view of the metal strip shown in Fig. 3, and

Fig. 5 is a cross-sectional view of a strip of metal before it is rolled into the drum flange stock, showing rou hly the quantity and relation of the high car on to the low carbon steel contained therein. 1

In general, I accomplish the objects of my invention by constructing a brake drum in 0 two parts and permanently connecting the It is an object of my invention to producev known manner.

parts together. The body part of the drum is composed of a hub having a flange preferably formed integrally therewith. The wearand high carbon steel, the steel of low carbon content forming the backing of the annulus and the steel of hi h carbon content forming the wearing surface.

If the drum flange is to be made of high carbon or both high and low carbon steel, the advantages of my construction are of redoubled value due to the fact that stock containing high carbon steel cannot effectually be die drawn In the production of a brake drum in accordance with my invention, there is no waste of material, and breakage due to die-drawing is completely eliminated because vnow die-drawing operation is required. The

sizing of the drum flange is readily and easily accomplished and the storage space problem is effectually solved. The difle'rence in the floor spacejrequired for storing flanged brake drums, impossible to nest, and strip drum .flange stock can readily be appreciated.

7 With reference to the drawings, hub 1 is provided with a circumferential flange 2 preferably formed integrally therewith. This integral formation of hub and flange may preferably be produced by forging a hub blank with a thick, circumferential flange of relatively short radius and then rolling and thinning this flange to produce the finished-flange of desired gauge and radius.

Adjacent the peripheral portion thereof, flange 2 is provided with a circumferential shoulder 3 against which inwardly projecting flange 4. ofthe drum flange 5 abuts. Apertures 6 in the hub flange are adapted to receive studs or bolts which retain either a disk or wire wheel on hub 1 in the wellinwardly and outwardly directed lateral flanges 4 and 8 respectively, these flanges being preferably formed or partially formed on the strip '7 before it is rolled or formed into an annulus. Following its formation into an annulus and the permanent joining of the abutting ends, flange 5 is put through an expanding and contracting operation to bring it to the exact desired size. The annulus is then mounted on hub flange 2 and preferabl permanently fastened thereto in an suitable manner as by rivets 9, and pro vi es the necessary braking surfaces 'for the drum on its inner and outer circumferential surfaces.

The flange 5 may be formed from strip metal stock composed entirely of relatively low carbon content or entirely of high carbon content or may preferab y be produced from strip stock containing oth low and high carbon steel, the low carbon portion forming the backing or base of the drum flange and the high carbon portion forming the wearing or braking surfaces of the drum.

Strip stock containing integral low and high carbon steel in layers of equal width may readilg be produced today by known methods. ut I have evolved a method by which a relatively thin layer of high carbon steel may be provided for the braking surface of the stock while the marginal portions which are to be flanged for strengthening and attaching purposes, remain of low carbon content. As shown in Fig. 5, a relatively thin and narrow stri of metal of high carbon content 11 is pre erably placed in an opening, sufliciently great to receive it, of a strip of metal 12 of low carbon content and of preferably U-shaped cross-section. This laminated strip is then hot rolled to produce the comparatively thinner and Wider stri stock 7 from which the drum flange 5 is formed, with the low and high carbon portions thereof integral. It is to be noted that the marginal portions of the strip stock are composed entirely of low carbon metal and thus may be readily formedto provide flanges forstrengtheninlg and attaching pur oses. By this method, produce brake drum flange strip stock with a strong and readily worked low carbon backing and flanges and a durable wearing surface of high carbon steel. Since much the greater proportion of this strip stock is composed 0 low carbon steel, it is apparent that no difliculty will be encountered in forming the strip into an annulus.

In the drawings, reference character 10 indicates the high carbon wearing or braking surface, and while I have shown such a surface only in the inner circumferential sur-' face of the drum flange, itis evident that the outer circumferential surface of the drum flange may also be provided with such a high carbon surface if it is desired to employ both internal ex ending and external contracting types 0 brake with a single drum. The economy possible in the manufacture of brake drums in accordance with my invention will at once be apparent. Every bit of the stock or raw material from which the drums are to be formed is utilized. Diedrawing not being employed in the manufacture of the drums, breakage and spoilin from this cause, is, of course,'elim1nate The ease and readiness with which the drum flange may be brought to exact size by expansion and contraction and the ease with which the strengthening and attaching flanges may be formed on the drum flange while yet providing a durable wearing surface of diflicultly worked high carbon steel contribute toward this economy of manufacture. And of equal importance, is the enormous saving in storage space made ossible by the utilization of my method. An finally by my improved method of forming the metal stock for the drum flange of integral high and low carbon steel, I am able to produce a strong, durable and yet easily worked material that contributes in a large degree to my success in cutting the cost of brake drum manufacture.

a The embodiment of my invention selected for illustration and description is to be considered a preferred one and it is to be understood that it is not my intention to limit my invention to that particular embodiment or otherwise than by the appended claims.

What I claim is:

1. The process of forming cylindrical brake drum bodies of material so hard as to be impracticably die drawn which consists in taking strip stock of the material of a width substantially equal to the cylindrical main body, the length approximating the circumference of the main body, bending said stock into an annulus of the diameter of the main body desired, and welding together the abutting ends of the annulus, and thereafter subjecting said annulus to an extending and contracting operation to size the body of the drum.

2. The method of making cylindrical brake drum bodies having wearing portions of material of a hardness rendering it impractical of being diedrawn which consists in constituting'strip stock in longitudinally extending zones alternately of the said hard material and a softer material, cutting said material into lengths equal to the length of circumference o the drum body to be formed, forming the cut lengths into annuli of the diameter of the drum body, welding together the abutting ends of the annuli, and

thereupon die drawing attaching flanges from a marginal strip zone of relatively soft material.

3. A cylindrical main body for a brake drum comprised of a circumferentially extended piece of strip stock of bendable material of a hardness approximately of the hardness of high carbon steel rendering it impractical for die drawing throughout the principal portion of its width, but having flanged marginal portions throughout of a material practically capable of being die drawn.

In testimony whereof he hereunto afiixes his signature.

GORDON M; EVANS. 

